a) Field of the Invention
The invention relates to the transfer of microstructures from a tool to a substrate which is to be structured, with supports for the tool and the substrate which can be adjusted in relation to one another in a direction resulting in an alteration of the distance between the tool and the substrate.
b) Description of the Related Art
A device of this type is known, for example, from DE 196 48 844 C1.
For transferring microstructures, it is known to press a molding tool into a moldable material, such as for example a layer of thermoplastic material, preferably under a vacuum and at a temperature above the softening temperature of the moldable material and, as a result, to produce three-dimensional structures with structure heights in the range of just a few nanometers up to several hundred micrometers.
A device suitable for this purpose, according to DE 196 48 844 C1, is capable of compensating for variations in thickness of molding tools and of moldable materials used, while ensuring high dimensional stability, and of ensuring different molding depths.
The device includes a chamber with a chamber part which is fixed to the framework and a chamber part which is adjustable, in which chamber the setting of the pressure and temperature conditions is linked to prescribed values of a force acting on the fixed chamber part.
It is disadvantageous in the case of this known device that the location at which the structures are to be transferred into the moldable material cannot be determined.
It is therefore the primary object of the invention to ensure that the tool and the moldable material can be mutually aligned in a manner which can be monitored.
According to the invention, the object is achieved by a device for transferring microstructures from a tool to a substrate which is to be structured, with supports for the tool and the substrate which can be adjusted in relation to one another in a direction resulting in an alteration of the distance between the tool and the substrate, in that, for measuring selected locations in at least one measuring plane, in relation to which the direction of adjustment of the supports is directed vertically, a measuring system which can be pushed in between the supports and, when in a measuring position, is in a fixed spatial relationship with the tool is provided, and in that the substrate can be displaced parallel to the measuring plane for alignment with respect to the tool.
The support for the tool is contained in a first chamber part and the support for the substrate is contained in a second chamber part of a closable chamber, in which the transfer of the microstructures takes place by molding.
The chamber is advantageously designed as a vacuum chamber or can be filled with inert gas.
The measuring system includes various optical branches with image fields of different sizes, the magnification of a first optical branch permitting easy searching for the locations to be selected and that of a second optical branch permitting exact measurement of the selected locations in the measuring planes.
A transporting device which contains different drives for positions to be moved to one after the other is provided for the pushing in of the measuring system, a first drive undertaking the transport from a first position outside the chamber into a second position in the opened chamber and a second drive moving the measuring system into a position aligned in relation to the tool. The measurement can be performed without hindering the molding.
The data ascertained are used for activating a device for displacing the substrate with respect to the tool which is contained in the second chamber part. The device includes two sliding plates which lie one on top of the other, are movable in relation to each other parallel to the plane of the substrate adjustment and of which an upper sliding plate serves as a chamber-closing element.
The upper sliding plate can preferably be clamped to the lower sliding plate.
The upper sliding plate can, furthermore, support a first part of a heating and cooling unit, on which a securing means for the substrate is fastened.
For changing the height of the chamber, the chamber may have side wall parts which provide a seal towards the outside and are themselves adjustable in relation to one another in the direction of the adjustability of the chamber parts.
It is advantageous if the tool is enclosed on its circumferential surface by a cylindrical tool holder, which is fastened in the first chamber part to a plate-shaped body.
The plate-shaped body may be in connection with a second part of a heating and cooling unit.
For removing the molded material from the tool, the tool holder may be enclosed at the lateral surface by a demolding tool, which is displaceable with respect to the tool holder in the direction of the mutual adjustability of the supports for removing the substrate from the tool following the transfer of the microstructures.
To ensure great stability over time of individual systems of the device, the measuring system, the displacing device and the first chamber part may contain channels for a temperature-controllable fluid.
For establishing the fixed spatial relationship between the measuring system and the tool, hooks for hanging on correspondingly shaped hooks of the first chamber part are fastened to the measuring system in the upper region of the latter.
It is also advantageous if the substrate comprises a supporting layer and a moldable material applied to the latter.
A tool for transferring structures into the moldable material may also be applied to the supporting layer.
The subject matter of the invention also includes a method for transferring microstructures from a tool to a substrate which is to be structured, with supports for the tool and the substrate which can be adjusted in relation to one another in a direction resulting in an alteration of the distance between the tool and the substrate. A positioning, required for the locationally exact transfer of the microstructures, of the substrate which is to be structured with respect to the tool in a plane in relation to which the direction of adjustment of the supports is directed vertically is ascertained by correction values for the positioning, determined by the distance of the microstructure from a mark on the substrate, being formed from measured structure positions of transferred microstructures on a first structured substrate for at least one further substrate to be structured.
To increase the positioning accuracy further, on the first substrate the positions of the marks may be additionally ascertained before and after the transfer of the microstructures for forming correction values for the positioning.
If the positioning accuracy is to be improved still further, the positions of marks on the substrate holder may be determined as correction values before a substrate is placed onto the substrate holder.
Finally, it is also advantageous if, after the molding of each substrate, ascertained positions of the molded microstructures and of the marks are used as correction values for the positioning of the substrate which is to be respectively structured thereafter.
With the present invention, the unchangeable spatial arrangement of the tool in relation to the moldable material prescribed in the case of the known technical solutions by the structural design is no longer applicable and their mutual alignment is ensured with high precision by ascertainment and manipulation of the positional relationships.
The invention is to be explained in more detail below with reference to the drawings.